The present invention relates to ventricular resynchronization therapy (VRT) devices. More specifically, the present invention relates to determining a coronary vein branch position of the coronary sinus lead of a VRT device.
Ventricular resynchronization therapy is one method of treating heart failure patients. VRT often requires that the left ventricle of a patient be electrically stimulated. This is especially true if there is a conduction disorder in the left ventricle of the heart whereby the fast conductivity fibers (i.e., pumping system) in the left ventricle are damaged. When the conduction fibers are damaged, electrical waves traveling through the heart no longer travel quickly through the high speed fibers but instead travel much slower as they pass sequentially through muscle conduction. This slowing of the wave propagation through the left ventricle may cause one part (usually the septum) of the ventricle to contract first and begin to relax before another part (usually the freewall) of the ventricle contracts.
One scenario is that the freewall of the ventricle tends to expand during the period of contraction of the septum. Once the freewall begins to contract, the septum has relaxed. As a result of the septum and freewall portions contracting at different times, blood is passed side-to-side within the ventricle rather than being efficiently pumped out into the arteries.
VRT attempts to improve the pumping efficiency of the heart by providing an electrical stimulation to a later contracting part of the ventricle, for example the freewall, contemporaneously with the natural contraction of the earlier contracting portion, such as the septum. Because both sides contract at approximately the same time with VRT, the volume of the left ventricle is significantly reduced and blood is effectively pumped out into the arteries. To provide such electrical stimulation, an electrode connected to a VRT device must be positioned near the delayed region of the ventricle. The delayed region may be accessed via a branch of the coronary sinus vein that extends over the portions of the left ventricle.
The most accessible branches of the coronary sinus vein include the lateral, posterior, and anterior branches. Creating an electrical stimulation in the lateral or posterior branch provides the best hemodynamic response and maximizes the benefit from VRT for patients with left ventricle conduction disorder. Therefore, it is desirable to place the electrode of the VRT device in the lateral or posterior branch instead of the anterior branch. Furthermore, the timing of the electrical impulse provided by the VRT device to the electrode must be set according to the position of the electrode to induce contraction of the delayed portion of the ventricle at the appropriate time. Thus, the location of the electrode must be known.
During installation of the electrode, fluoroscopy is used to determine the position of the lead, and fluoroscopy exposes the patient to X-ray radiation. If the patient has an abnormal coronary sinus vein system, then fluoroscopy may become unreliable in determining the location of the electrode. Additionally, unusual anatomy may require a longer fluoroscopy exposure time. Thus, using fluoroscopy to determine electrode position during installation has drawbacks.
Thus, it is desirable to provide a method and system that enables the position of the electrode in the left ventricle to be determined without or in addition to fluoroscopy, to automatically configure the VRT device based on the detected position, and to display in real-time the detected position on a video display.
Embodiments of the present invention assist in installation and/or setup and identification of an electrode in the left ventricle area of a patient""s heart. These embodiments involve detecting electrical events in the patient""s heart and then determining the position of the left ventricle (LV) electrode from measurements of the electrical events.
The present invention may be viewed as a method for determining a position of a first electrode placed within a left ventricle area of a patient""s heart. The method involves detecting a first depolarization event within the heart and sensing, with the first electrode, a second depolarization event within the heart. The method further involves measuring a first interval between the first depolarization event and the second depolarization event and determining from at least the first interval whether the lead has a lateral/posterior position or an anterior position within the left ventricle.
The present invention may be viewed as another method for determining a position of an electrode within a left ventricle of a patient""s heart. This method involves detecting a first depolarization event within the heart and sensing, with the electrode, a second depolarization event within the heart. The method also involves measuring a first interval between the first depolarization event and the second depolarization event and detecting a third depolarization event within the heart. A second interval is measured between the third depolarization event and the second depolarization event, and the electrode position is determined based on an evaluation of the first and the second intervals.
The present invention may be viewed as a system for determining the position of a first electrode in a left ventricle area of a patient""s heart. The system includes one or more detection devices for detecting at least first and second electrical events in the patient""s heart, one of the one or more detection devices being electrically connected to the first electrode and detecting the second electrical event in the left ventricle area. The system also includes a processing device in electrical communication with the one or more detection devices. The processing device is configured to calculate a first interval between the first and second electrical events and determine the position of the electrode based at least upon the first interval.
The present invention may be viewed as another system for determining the position of a first electrode in a left ventricle area of a patient""s heart. This system includes means for detecting a first electrical event within the patient""s heart, means for detecting a second electrical event occurring at the first electrode, and means for determining whether the first electrode has an anterior or lateral/posterior position within the left ventricle based at least on a first interval between the first and second electrical events.
The present invention may be viewed as a method for assisting installation of an electrode in a left ventricle of a patient""s heart. This method involvesplacing the electrode in a coronary sinus vein branch of the left ventricle and detecting a plurality of electrical events in the patient""s heart during a heart beat, wherein at least one of the plurality of electrical events is sensed by the electrode. The method also involves determining from the plurality of electrical events whether the electrode has an anterior or a lateral/posterior vein branch position during the heart beat and displaying on a display screen an indication of the determined position of the electrode.
The present invention may be viewed as a method for assisting installation of an electrode of a VRT device in a left ventricle of a patient""s heart. The method involves placing the electrode in a coronary sinus vein branch of the left ventricle and detecting a plurality of electrical events in the patient""s heart during a heart beat, wherein at least one of the plurality of electrical events is sensed by the electrode. The method also involves determining from the plurality of electrical events whether the electrode has an anterior or a lateral/posterior vein branch position during the heart beat and adjusting settings used by the VRT device based upon the determined position of the electrode.